Question

log base3 (x+7) + log base3 (x-1)=2 como faz ?

Answer 1

Olá, Calculo01.

 

$<var>\log_3 (x+7) + \log_3 (x-1)=2 \Rightarrow \log_3[(x+7)(x-1)]=2 \Rightarrow\\\\ (x+7)(x-1)=3^2 \Rightarrow x^2-x+7x-7=9 \Rightarrow x^2+6x-16=0\\\\ \Rightarrow x=\frac{-6 \pm\sqrt{36+64}}2=\frac{-6\pm10}2\\\\ \therefore\boxed{x=2\text{ ou }x=-8}</var>$